1. Field of the Invention
The present invention relates to a system and procedure to transfer a load from a cargo barge to a substructure. More particularly, the present invention relates to a system and procedure to transfer, at sea, a load on the fixed legs emerging from water of a substructure, said load specially fabricated in the construction yard and transported to said substructure by a suitable cargo barge.
2. Description of the Related Art
In the state of the art, other systems are already known to transfer at sea loads from cargo barges to platforms. The transfer has been performed, until now, by lifting the load to be transferred by middle/big pontoons or crane vessels, subdividing said loads in multiple modules depending on the weight of the load to be lifted. This well known method has however always required the operator to maintain the loads to be transferred within preestablished limits due to many problems among which, first of is the availability of middle/big pontoons or crane vessels and their cost which is indeed very expensive.
Many other methods have been known in the art. One of the most recent is that one reported, for example, by W. D. Martell and S. M. Beattie of Enercon Eng. Inc. on: "Integrated float-over deck design considerations" which was presented at the Offshore Technology Conference, O.T.C. 8119, held in Houston, Tex., from 6 to May 9, 1996. There the authors detailed the installation of two large modules by the transfer from a cargo barge to a substructure in the South China Sea (M-Field) for Shell Sarawak.
This installation has required the mooring of a cargo barge, suitably prepared with an integrated module therein charged, inside the opening of a substructure fixed to the bottom of the sea. The structure emerges from the sea level with two towers having four legs each; the subsequent lowering of the cargo barge is made by ballast pumped inside the transport vessel, in order to transfer gradually the weight of the load from the cargo barge to the substructure.
This experience has shown, even to the participants at the installation, the real possibility to transfer big loads at sea world wide, assuming that the significant wave height and the relevant impact value between cargo barge side and substructure legs, remain within preestablished and acceptable values.